Use volume key to select wipe data / factory reset and Press Power key to confirm

One more, use volume key to select wipe data / factory reset and Press Power key to confirm

Use volume keys to select Reboot system now to finish hard reset and press Power key to confirm

Hard reset using Settings Menu

Turn on the device

Select Apps

Select Settings

Select Backup and reset

Select Factory data reset

Select Reset device

Select Erase Everything

Select Ok

Warning! If you perform a hard reset, make sure to back up important data. The data can not be recovered after perform a hard reset. If you forgot your unlock pattern, It will remove your forgotten pattern unlock.